Apparatus for detecting metal particles



July 26, 1949.

INVENTOR.

CHARLES a. GRAnv, JR. BY

ATTORNEYS.

Patented July ze, 1949 APPARATUS FOR DETECTING METAL PARTICLES Charles B. Grady, Jr., West Orange, N. J., assignor to Celanese Corporation of America, a corporation of Delaware Application January 1l, 1946, Serial No. 640,615

2 Claims.

This invention relates to a novel detecting device, and relates more particularly to an improved device for the detection of stray metal bodies in a moving mass of non-metallic material in particle fo'rm.

An object of this invention is to provide a novel detecting device to be employed in connection with a belt conveyor system, or the like, carrying certain fibrous materials, whereby the presence of metal bodies in said fibrous materials may be readily determined and indicated by suitable means.

Other objects of this invention will appear from the following detailed description and the accompanying drawing.

In the drawing, the figure is a, perspective view, partly broken away, showing a portion of a 'belt conveying system having in combination therewith and attached thereto the novel detecting device of my invention.

Referring now to the figure of the drawing, the belt conveying system, which is generally indicated by reference' numeral I, comprises as the main element a flexible belt 2 having a plurality of metal supporting rods 3 fixed in the supporting rails 4 at spaced intervals along slots 5 in said rails. 'I'he rods 3 are set in roller bearings 6 and provide the desired degree of lateral sup- Dort for said belt 2. The rods 3 and the bearings 6 are stationary. The supporting rails 4 are set upon or supported' by suitable framework (not shown), the path of the conveyor belt 2 being defined by the direction and angle. at which the supporting rails 4 are placed. The belt 2 is driven by suitable driving means (not shown) and the roller bearings B serve to minimize any friction which may develop as said belt moves.

The conveyor belt 2 may be employed to transport any wet or dry material In particle form from point to point. In accordance with this invention, means are provided to detect the presence of stray metal bodies in the material moving on belt 2, said means comprising a pair of coils 1 and 8. The coil l is attached to rails 4.

by insulated blocks 9 and in a plane at right angles to belt 2 while the coil 8 is parallel to the direction of movement of said belt 2 and is atcut-oif. Normally, the coil 8 will pick up no energy from the coil l due to the angular disl placement of the field of the coil 1 from the coil tached to the rails 4 by insulated blocks I0. The

8. When a piece of stray metal enters the field of coil l, however, the field is distorted and the coil 8 thereupon picks up some energy from the resulting distortion of the eld. By a suitable amplification of the energy fiowing through coil 8 in the several amplification stages, the resulting energy in the last stage is then caused to operate a switch or relay C and thus to flash a suitable warning signal D, or to stop the conveyor automatically or divert that portion of the material containing the foreign body from the main body in any suitable manner. The removal of the stray metal in the material on belt 2 is thus accomplished before the metal body can injure any machinery to which said material is being fed.

f It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from the spirit of my invention.

Having described my' invention, what I desire rounding said conveyor belt so that the axes of said coils are atright angles to each other and intersect inthe plane of said belt, 'the rstnamedv coil being connected to an ampliler and the last-named coil being connected to a high frequency oscillator, whereby any distortion of the field of the energized coil due to the presence of metal bodies in the material on the conveyor belt causes energy to be picked up by the first-named coil and fed into the amplifier to be amplified and converted into a desired signal or impulse.

2. In a conveying system, the combination of a conveyor belt supported on rotatable metal rods and normally carrying a non-metallic material in particle form thereon and a pair of substantially flat coils associated therewith, one of said coils being horizontal to and substantially within the plane of said conveyor belt and the second being in a plane perpendicular to the direction of movement of and surrounding said belt so 3 4 that the axes of said coils are at right angles to v each other and intersect m the plane of said hele, UNITED STA'I'ES PA'IENTS the mst-named coil being connected to an am- Number Name Date plier and the last-named coil being connected 1,640,524 Augustine Aug. 30, 1927 to a high frequency oscillator. whereby any dis- 5 1.812.392 Zuschlag June 30, 1931 e tortion of the tleld of the energized coil due to 2.228.294 Wurzbach Jan. 14, 1941 the presence of metal bodies in the material on 2,237,254 Broekhuysen Apr. 1, 1941 the belt causes energy to be picked up by the OTHER REFERENCES mst-named coil and fed into the amplifier to be amplied and converted into a desired signal or 10 Dept. 011116 Interior, Bureaul of Mines Inforimpulse. mation Circular 6854, dated October 1935, pages CHARLES B. GRADY, Jn. 12 and 13 and Figs. 14 and 15. REFERENCES CITED The following references are of record in the 16 Sfile of this patent: 

